Two-Step Wafer Edge Trimming for Deep Cuts Without Cracks
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Solution Overview
Problem
Conventional edge trimming methods for wafers bonded via a bonding layer face issues such as cracks in the second wafer due to cutting particles generated in the first wafer, and incomplete cutting of the first wafer's peripheral edge portion when using up-cutting, leading to uneven wear and shallow cuts.
Innovation Solution
A two-step trimming process involving a first trimming step with a cutting blade rotating from the second wafer side to the first wafer side, followed by a second trimming step with a cutting blade rotating from the first wafer side to the second wafer side, allowing for deeper cuts and effective removal of the peripheral edge portion without damaging the second wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If down-cutting is used to trim the peripheral edge portion, then the cutting blade can bite into the first wafer effectively, but cutting particles generated in the first wafer press against the second wafer causing cracks
Solution Approach 1:
The edge trimming process is divided into two distinct steps: a first trimming step using up-cutting to remove the peripheral edge portion without generating harmful cutting particles, and a second trimming step using down-cutting to achieve the target cutting depth. This segmentation allows each step to perform its specific function optimally without the harmful effects of the other.
Solution Approach 2:
The first trimming step performs preliminary cutting to remove the peripheral edge portion and prevent the generation of harmful cutting particles before the second trimming step. This preliminary action eliminates the source of the harmful effect (cutting particles) before they can cause damage to the second wafer during the final cutting operation.
2Object-affected harmful factors
If up-cutting is used to trim the peripheral edge portion, then cracks in the second wafer can be avoided, but the cutting blade escapes upward making cuts shallower than the target depth
Solution Approach 1:
The edge trimming process is divided into two distinct steps: a first trimming step using up-cutting to remove the peripheral edge portion without generating harmful cutting particles, and a second trimming step using down-cutting to achieve the target cutting depth. This segmentation allows each step to perform its specific function optimally without the harmful effects of the other.
Solution Approach 2:
Instead of using only up-cutting and trying to achieve deep cuts that way (which causes the blade to escape), the invention inverts the approach by using up-cutting first for shallow preliminary cuts to remove the peripheral portion, then switching to down-cutting for the final deep cut. This inversion of the conventional single-step approach resolves the contradiction.
3Device complexity
If a single trimming step is used, then the process is simple, but it cannot simultaneously prevent cracks and achieve complete cutting depth
Solution Approach 1:
The edge trimming process is divided into two distinct steps: a first trimming step using up-cutting to remove the peripheral edge portion without generating harmful cutting particles, and a second trimming step using down-cutting to achieve the target cutting depth. This segmentation allows each step to perform its specific function optimally without the harmful effects of the other.
Solution Approach 2:
The first trimming step performs preliminary cutting to remove the peripheral edge portion and prevent the generation of harmful cutting particles before the second trimming step. This preliminary action eliminates the source of the harmful effect (cutting particles) before they can cause damage to the second wafer during the final cutting operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively prevents cracks in the second wafer and ensures complete removal of the peripheral edge portion at the desired depth, reducing the risk of uneven wear and incomplete cutting.
Implementation Method 1
cutting and removing the peripheral edge portion of the workpiece on the first wafer side while allowing a first cutting blade to cut into the peripheral edge portion
Data Source
AI summary
A workpiece processing method includes: a first trimming step of cutting and removing the peripheral edge portion of the workpiece on the first wafer side while allowing a first cutting blade to cut into the peripheral edge portion; and a second trimming step of cutting and removing the peripheral edge while allowing a second cutting blade to cut into the peripheral edge portion from the first wafer side of the workpiece at a predetermined cut depth deeper than the cut depth of the first trimming step. The first trimming step includes rotating the first cutting blade in a rotation direction of cutting the workpiece from the second wafer side toward the first wafer side. The second trimming step includes rotating the second cutting blade in a rotation direction of cutting the workpiece from the first wafer side toward the second wafer side.